The purpose of this investigation is to determine the antibody response in primates to antigens administered by gastric intubation followed by intramucosal injection of same antigens. It was observed that animals vaccinated by using whole S. mutans (6715) through gastric intubation developed antibodies to the a-d antigen, and lipoteichoic acid. Functional inhibitory antibodies to glucosyl transferase were not detected. However, following a single injection of cells intramucosally in animals previously dosed intragastrically antibodies to glucosyltransferase developed which remained elevated for more than 6 months. Antibody was in the IgG class. The possibility of developing a vaccine against caries has become increasingly attractive in recent years. However, concern has been expressed that the injection of Streptococcal devised antigens may give rise to tissue reacting antibodies. It has therefore become imperative to determine whether protective levels of antibodies can be induced by administering antigens through a variety of routes.